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Tiger shark

2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and
Fish

                   iTiger shark

                             Conservation status

   Near Threatened (LR/nt)
            Scientific classification

   Kingdom:  Animalia
   Phylum:   Chordata
   Class:    Chondrichthyes
   Subclass: Elasmobranchii
   Order:    Carcharhiniformes
   Family:   Carcharhinidae
   Genus:    Galeocerdo
             Müller & Henle, 1837
   Species:  G. cuvier

                                Binomial name

   Galeocerdo cuvier
   Péron & Lesueur 1822
   Tiger shark range
   Tiger shark range

   The tiger shark, Galeocerdo cuvier, one of the largest sharks, is the
   only member of the genus Galeocerdo. Mature sharks average 3.25 – 4.25
   m (10 – 14 ft) and weigh 385 – 635 kg (850 – 1400 lb). It is found in
   many of the tropical and temperate regions of the world's oceans, and
   is especially common around islands in the central Pacific. This shark
   is a solitary hunter, usually hunting at night. Its name is derived
   from the dark stripes down its body, which fade as the shark matures.

   The tiger shark is a dangerous predator, known for eating a wide
   variety of items. Its usual diet consists of fish, seals, birds,
   smaller sharks, squid and turtles. It has sometimes been found with
   detritus such as license plates or pieces of old tires in its digestive
   tract. It is notorious for attacks on swimmers, divers and surfers in
   Hawaii; and is often referred to as the "bane of Hawaiian surfers" and
   "the wastebasket of the sea".

   The tiger shark is second only to the great white in number of recorded
   human fatalities and is considered, along with the great white, bull
   shark and the oceanic whitetip shark to be one of the sharks most
   dangerous to humans.

Taxonomy

   The shark was first described by Peron and Lessueur in 1822 and was
   given the name Squalus cuvier. Müller and Henle, in 1837 renamed it
   Galeocerdo tigrinus. The genus, Galeocerdo, is derived from the Greek,
   galeos which means shark and the Latin cerdus which means the hard
   hairs of pigs. It is often colloquially called the leopard shark and
   the man-eater shark.

   The tiger shark is a member of the order Carcharhiniformes; members of
   this order are characterized by the presence of a nictitating membrane
   over the eyes, two dorsal fins, an anal fin, and five gill slits. It is
   the largest member of the Carcharhinidae family, commonly referred to
   as requiem sharks. This family includes some other well known sharks
   such as the blue shark, lemon shark and bull shark.

Distribution

   The tiger shark is often found close to the coast, in mainly tropical
   and sub-tropical waters, though they can reside in temperate waters.
   The shark's behaviour is primarily nomadic, but is guided by warmer
   currents, and it stays closer to the equator throughout the colder
   months. The shark tends to stay in deep waters that line reefs but does
   move into channels to pursue prey in shallower waters. In the western
   Pacific Ocean, the shark has been found as far north as Japan and as
   far south as New Zealand.

   The shark has been recorded down to a depth of 350 m (1085 ft) but is
   also known to move into shallow water - water that would normally be
   considered too shallow for a species of its size. It is also frequently
   found in river estuaries and harbours. At night it is usually found in
   shallow water.

Anatomy and appearance

   Closeup of tiger shark teeth showing the distinctive serrated edges.
   Enlarge
   Closeup of tiger shark teeth showing the distinctive serrated edges.

   Its skin can typically range from a blue or green hue to light with a
   white or light yellow underbelly. The distinguishing dark spots and
   stripes are most outstanding in young sharks and fade as the shark
   matures. Specimens regularly weigh up to 1 tonne (2,200 lb). It is
   usually 3 to 5 m (10 to 16 ft) long, but there have been confirmed
   specimens as large as 6.4 m (21.5 ft). The heaviest specimen recorded
   to date, a shark caught in Newcastle, NSW, Australia in 1954 and
   measuring a mere 5.5 m (18 ft), scaled 1,524 kg (3,360 lb). Sexual
   maturity is reached at different stages for each of the sexes; males at
   2.26 to 2.9 m (7 to 9 ft) whereas females mature at 2.5 to 3.25 m (8 to
   10 ft). It has been estimated that the tiger shark can swim at a
   maximum speed of around 32 km/h (20 mph), with short bursts of higher
   speeds that last only a few seconds.

   The tiger shark's head is somewhat wedge-shaped, which makes it easy
   for the shark to turn quickly to one side. Tiger sharks, as with other
   sharks, have small pits on the side of their upper bodies which hold
   electrical sensors enabling them to detect small muscle movements of
   other creatures, allowing them to hunt in darkness. A tiger shark
   generally has long fins and a long upper tail; the long fins act like
   wings and provide lift as the shark maneuvers through water, whereas
   the long tail provides bursts of speed. A tiger shark normally swims
   using lithe movements of its body. Its high back and dorsal fin act as
   a pivot, allowing it to spin quickly on its alliance.

   Its teeth are flat, triangular, notched and serrated. Like most sharks,
   when a tiger shark loses or breaks one of its teeth, it grows a
   replacement tooth. The distinctive teeth seem to have evolved to be
   able to cut through turtle shells, and an adult tiger shark can easily
   bite through bone.

Diet

   The tiger shark, which generally hunts at night, has a reputation for
   eating anything it has access to, ignoring what nutritional value the
   prey may or may not hold. Apart from what is thought to be sporadic
   feeding, its most common foods include; common fish, squid, birds,
   seals, other sharks, and sea turtles. The shark has a number of
   features which make it a good hunter, such as excellent eyesight, which
   allows for access to murkier waters which can offer more varieties of
   prey and its acute sense of smell which enable it to react to faint
   traces of blood in its waters and is able to follow them to the source.
   The tiger shark's ability to pick up on low-frequency pressure waves
   produced by the movements of swimming animals, for example the
   thrashing of an injured animal, enables the shark to find a variety of
   prey.

   The shark is known to be aggressive. The ability to pick up
   low-frequency pressure waves enables the shark to advance towards an
   animal with confidence, even in the environment of murky water where it
   is often found. The shark is known to circle its prey and even study it
   by prodding it with its snout. When attacking the shark devours all of
   its prey. Because of its aggressive nature of feeding, it is common to
   find a variety of foreign objects inside the digestive tract of a tiger
   shark. Some examples of more odd items would be automobile number
   plates as well as petroleum cans and tires.

Reproduction

   A tiger shark caught in Kaneohe Bay, Oahu in 1966.
   Enlarge
   A tiger shark caught in Kaneohe Bay, Oahu in 1966.

   The tiger shark breeds by internal fertilization. It is the only
   species in its family that is ovoviviparous; like mammals, it gives
   birth to live young. The male tiger shark will insert one of its
   claspers into the female's genital opening, acting as a guide for the
   sperm to be introduced. The male uses its teeth to hold the female
   still during the procedure, often causing the female considerable
   discomfort. Mating in the northern hemisphere will generally take place
   between the months of March and May, with the young being born around
   April or June the following year. In the southern hemisphere, mating
   takes place in November, December, or early January.

   The young are nourished inside the mothers body for up to 14 to 16
   months, where the female can produce a litter ranging from 10 to 80
   young. A newborn tiger shark is generally 51 to 76 cm long and leaves
   its mother upon birth. It is unknown how long tiger sharks live, but it
   has been speculated to be 20 years.

Dangers and conservation

   Although shark attacks on humans are a relatively rare phenomenon, the
   tiger shark is responsible for a large percentage of the fatal attacks
   that do occur on humans, and is regarded as one of the most dangerous
   species of sharks. Tiger sharks reside in temperate and tropical
   waters. They are often found in river estuaries and harbours, as well
   as shallow water close to shore, where they are bound to come into
   contact with humans. Because of their curious nature of feeding it is
   expected that a tiger shark would normally attack a human if it came in
   contact with it. Tiger sharks are known to dwell in waters with runoff,
   such as where a river enters the ocean.

   Tiger sharks have become a recurring problem in Hawaii and are
   considered the most dangerous shark species in Hawaiian waters. They
   are considered to be sacred 'aumakua' or ancestor spirits by the native
   Hawaiians, however between 1959 and 1976, 4,668 tiger sharks were
   hunted down in an effort to control what was proving to be detrimental
   to the tourism industry. Despite these numbers, little decrease was
   ever detected in the attacks on humans. It is illegal to feed sharks in
   Hawaii and any interaction with them such as cage diving is
   discouraged.

   The tiger shark is not directly under attack by commercial industries.
   There is, however, a usual sequence of activities which sees the shark
   harvested for its fin and flesh. A tiger shark's liver, as with most
   sharks, is considered to be of high value as it contains a high vitamin
   A content, which is extracted to produce vitamin A oil. Similar to many
   other sharks, its skin is a valuable commodity for the handbag
   industry. A tiger shark's skin is sturdy and considered exotic for its
   striped tiger-like appearance.

   Retrieved from " http://en.wikipedia.org/wiki/Tiger_shark"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
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